A majority of pregnant women receive some kind of test, including maternal serum screening and/or an ultrasound test, to determine risks for common birth defects, such as those resulting from trisomy 13, 18, and 21 (Down Syndrome). Both the sensitivity and specificity of these common non-invasive screening tools are extremely poor. The best current non-invasive tests lead to a false positive rate between 7 and 20%. This high false positive rate often causes individuals to opt for invasive diagnostic tests, such as chorionic villus sampling (CVS) and amniocentesis. Such invasive tests each carry a fetal loss rate of 0.5%-1% and account for the loss of thousands of normal fetuses annually. However, prenatal diagnosis can be critical for management of a pregnancy with chromosomal abnormalities and localized genetic abnormalities, because an accurate and early diagnosis allows for interventional care before or during delivery and can prevent devastating consequences for the neonate. The development of a non-invasive test for genetic abnormalities that is sensitive and specific with low false-positive and false-negative rates would be of benefit to the field of molecular diagnostics.